This application relates to an improved nozzle for applying a fluid to a surface to be cleaned. More particularly, this invention relates to such a nozzle in which a member is positioned within the nozzle to create cavitation and apply a cavitating jet to thoroughly clean the surface, and wherein the nozzle is rotated to clean a large surface area efficiently.
Modern cleaning systems often use a fluid jet to remove rust, scale or coatings from a surface to be cleaned. Typically, these surfaces are cleaned by the application of a fluid which carries an abrasive substance, such as sand. The use of a fluid carrying an abrasive is well known and commonly utilized to clean surfaces such as metal down to a bare metal surface. In many prior art systems, the use of a fluid without a abrasive material would not effectively clean the surface.
It is sometimes undesirable to use an abrasive carried in a fluid, since the abrasive may escape from the fluid and be mixed into the air surrounding the cleaning area. Further, the abrasive material may get into nearby machinery. Further, the abrasive material may contaminate environmental air and/or water. All these results are undesirable. For this reason, it is desirable to develop a cleaning system that utilizes a fluid jet which does not carry an abrasive material.
It is known in the prior art to utilize cavitation to increase the cleaning power of a fluid jet. Essentially, the principle of cavitation involves lowering the pressure of a fluid below its vapor pressure. As the fluid reaches pressures below the vapor pressure, bubbles of vaporized fluid form in the jet. As the jet strikes a surface to be cleaned, these bubbles implode and remove rust, scale or other impurities. Cavitation may be undesirable in pumping fluids and for other fluid applications, however, it is beneficial in cleaning applications.
Problems exist with prior art nozzles which utilize cavitation since it is difficult to cause an adequate cavitation effect in a mass produced nozzle. It should be appreciated that in order for the nozzle to actually produce substantial cavitation bubbles, internal members must be accurately formed and positioned.
In some prior art devices, a pin member is received in the nozzle to lower the pressure of the fluid, thereby creating cavitation. It has been found that this pin member should be accurately positioned within the nozzle and centered along a nozzle center axis. It is very difficult to center and to maintain the pin centered within the nozzle. These fixed pins often moved off-center with use, which decreased the efficiency of the cavitating nozzles. Further, it is difficult to accurately set the axial position of the pin, which is an important variable in the efficiency of a cavitation nozzle. In addition, since these prior art pins were typically fixed relative to the nozzles, close attention was required during assembly to ensure that the pins were centered within the nozzles. This has resulted in the prior art cavitating nozzles being less efficient than desired.
In addition, it has been known to supply a pressurized fluid from nozzles mounted in a rotating head. The use of such nozzles allows relatively wide coverage on a surface to be cleaned, since the nozzles are rotated through an arc rather than directed along a single line. The prior art rotating heads are often rotated by forces from the pressurized fluid. The use of such nozzles has provided a number of benefits, however, there are some deficiencies in the use of these rotating fluid heads.
As explained above, the use of a pressurized fluid by itself has not adequately cleaned certain surfaces. Further, the use of the fluid by itself takes a relatively long period of time to clean the surface. The high rotational speeds which are available from a high pressure fluid could allow very rapid cleaning of large surfaces. It would be preferable to utilize the cavitation principle discussed above in combination with a rotating fluid head, such that the jet exiting a nozzle will quickly and efficiently clean the surface.
It is therefore an object of the present invention to disclose a cavitating jet nozzle mounted in a rotating fluid head for the purposes of cleaning a relatively large area in a relatively short time.